Adjustable muscle stretching device



FIG. 1 is a top plan view of an adjustable muscle stretching device showing my new design;

FIG. 2 is an end view, the opposite end being a mirror image thereof;

FIG. 3 is a top perspective view thereof; and,

FIG. 4 is a left side view of an adjustable muscle stretching device showing my new design, the right side being a mirror image thereof. 

CLAIM The ornamental design for an adjustable muscle stretching device, as described and shown. 